The present invention relates to cooling apparatus for an electronic device including a semiconductor chip is incorporated and, more particularly, to cooling apparatus for enabling cooling in accordance with an amount of heat generation and which is suitable for preventing deformations or some other unfavorable phenomena of the semiconductor chip.
Arrangements wherein a radiator fin or a thermal diffusion plate such as a thermal conductive layer is directly attached to a casing of LSI chips mounted on a board in order to increase an amount of heat radiation are disclosed in, for example, "Electronics", August 1989, p. 29, and Japanese Patent Unexamined Publication No. 63-289847.
In these conventional arrangements, an electronic device is integral with a heat sink of a specific configuration. Consequently, when the electronic device is operated in such a manner that the amount of heat generation in chips incorporated in the device is larger than the amount of heat absorption by the heat sink, it is necessary to attach, to the electronic device, a heat sink of a different configuration to accomodate the circumstances. However, a connection method which is excellent in heat conduction and highly reliable must be employed every time such replacement is conducted, and such cooling arts are not flexible enough for cooling of the entire system.
Another arrangement is disclosed in Japanese Patent Unexamined Publication No. 61-74356, wherein a cooling jacket is fixed onto a plurality of semiconductor chips by bolts, with an elastic member of fibrous cotton having high thermal conductivity being interposed therebetween so as to cool the semiconductor chips.
In last-mentioned conventional arrangement, the elastomer is designed to be a thin layer to improve the thermal conductivity. Consequently, unless the jacket is attached to the semiconductor chips with high accuracy, an undue force is exerted on the chips. As a result, the semiconductor chips can not be cooled in accordance with the respective amounts of heat generated by the respective chips, and this arrangement is not flexible enough for cooling of the entire device system.
A further arrangement is disclosed in Japanese Patent Unexamined Publication No. 1-286455, wherein a ribbed thermal conductive member is provided on a semiconductor chip mounted on an insulating board, and a heat sink, including a radiator fin, is attached to the ribbed thermal conductive member with presssure springs and rotary ball members interposed therebetween, which heat sink can be detached and is guided and moved in directions parallel to the insulating board by a guide mechanism of the ribbed thermal conductive member.
In this last-mentioned conventional arrangement, although the heat sink is detachable, the pressure springs tend to cause the force to affect the insulating board and the ribbed thermal conductive member, resulting in a force that will break the semiconductor chip. Additionally, high assembly accuracy is required for improving the thermal conductivity.